Automatic fire-alarm.



L1 BOBILLOT.

AUTOMATIU FIRE ALARM.

APPLIGATION FILED 13110.1,1909- 1,008,370. Patented Nov. 14,1911. f l

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ffm/ffm" Wmv/'W LOUIS BOILLOT, OFBESANCON, FRANCE.

AUTOMATIC FIRE-ALARM.

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Speoication of Letters Patent.

Patented Nov. 14, 1,911.

Application led December 1, 1909. Serial No. 530,809.

To all whom it may concern:

-zen of theRe ublic of France, No. 6 Square t. Amour,

in Automatic Fire-Alarms, of which the following is a specification.

Automatic fire alarms at present employed are usually contrivancesdependent upon the expansion of metals or gases under the in- `fluenceof heat, or upon the ready fusibility of certain fatty substances ormetallic alloys.

These insulated contrivances, which should be installed in large numbersto aii'ord appreciable security, are connected to electric alarmcontrivances, -by conductors which may be broken in case of lire, beforethe alarm devices have performed` their func-` tion. In addition thesecontrivances are frequently ineffective by reason of their tardy action.

The present ,invention has for its object the provision of analarl'nwhich shall afford really eilicient protection to premises andbuildings against fire, and relatesrspeciically to the construction ofthe cable ernployed in devices of this character. This alarm utilizesthe destructive' action of fire and the expansive actions produced byheat to effect a contact between two insulated electric conductors,situated very near one another, whereof the insulating covering isdestroyed almost instantaneously by -lames -the conductors beingconstructed and connected to an electric battery, and to electric alarmdevices in a manner which will be described by reference to theaccompanying drawing in whichz-- i y y Figure 1 is a diagrammaticrepresentation of the installation, and r-Figs 2 and 3 are larger scaleviews of two examples of constructlon of a cable carrying bilar strandswhich constitute the chief element of this invention. Figs. 4 and 5 aretransverse sectional views of complete cables of thert pes illustrated,respectively, in Figs. 2 an 3.

For the purpose of this invention an electric circuit comprises twoconductors a, b, insulated from one another, and also insulated at oneof their extremities a1, b1. At

i their. other extremities the two conductors i are connected, the'oneat b2 to the positive Be it known that I, Louis Rornror, citi residingat. Besanon, France, have invented new and useful Improvements pole ofan electric battery c, the other at az to the negative pole of the samebattery through the medium of an indicator el, comprising the localcircuit e, j of an electric bell system g. The indicator d and :he bellor bells g which are in series, are installed in places chosen so thatthey are under watch night and day. When any ame reaches the alarmcircuit, contact between the two conductors a, b, is brought about bymeans of the arrangement described above, und the alarm is give l V Tworeturn wires las', connected tothe two wires a, b, of the alarm circuitat their free ends a1, b1, are led to the place of observation, wherethey are joined to the two terminals of a junction piece j, 1:, whichallows the effective condition of the circuit and the proper workingcapability of the alarm contrivance to be tested at any moment. The

indicator d has-as many indicating surfaces as there are alarm circuitsin the establishment to be protected. A separate jtnction is employedfor testing each of the 11n es.

consequence of its great flexibility, its strength, its small sectionand its lightness, the said electric cable alarm lendsitself to amultiplicity of combinations, and to' very varied applications to.installations fcr 4protection against fire. It may be applied invarious other ways.

The new cable would advantageously be used as a double wire in rooms forall Intlar electric installations of low voltage, especially fortelephone and bell. installations. The use of this cable, the price'o'fwhich is very small, would simplify installation and lessen thebreakdowns and expenses of upkeep which are considerable items inconnection with leads now in use. Thr twowire electric cable alarm canbe equally7 well applied to electric apparatus for protection againstburglary, since, as said above, the two threads whlch compose it makecontact with one another, and can consequently cause the actuation of abell, through the medium of an indicator, when the cable is cut by anyinstrument. One r-nn obtain complete security in respect cf lhis latterapplication, and also for protection against arson by adopting thcfollowing form for the electric cable alarmlzv-As shown .in transversesection in Fig. 4, on a very much cnlarged scale, the new cablev isprimarily composed of six wires of copper or other metal of a very smalldiameter, each being covered with a ver thin layer of silk thread orother insu ating material c', the wire being twisted together in pairsso as to form three bifilar strands. rI'hese three strands are locatedin three equidistant helical grooves m, n, o, formed 1n a wire p ofCoppel` or other metal, and constituting the safety core of the cable.The cable thus formed is then covered with a thin layer of cotton threador other soft material d', and finally with a tube e of metal of fusibleallo The grooves` above referred to are of a depth at least as eat as,and preferably greater than, the iameter of these twisted strands, thepurpose of this .construction being to hinder tampering with thestrands, but should the strands be molested then owin to the fit thereofin the grooves, and the t 'n insulation around the strands it would bepractically impossible to interfere with one strand without affectin theother and thus giving the alarm. or certain parts of installations, laflexible conductor could under the same conditions be vemployed, themetallic tubular protector being rep aced by a winding of tape.

The six conductors of the cable or of the flexible conductor alarm,distinguished by insulating coverings of different colors could be emloyed at need, to form one, two or three dou le wire circuits, of whicheach wire of the circuit will be composed of one or more elements byconnecting in each bilar strand one element to one of the threads a of acircuit, and the other element to the second thread b of the circuit(Fig. According to the exampleabove, cable and flexible conductor alarmswith two or four strands could also be constructed, by means of one ortwo strands formed of two insulated conductors twisted together, andlocated in one or two helical grooves in the metallic safety core.vCables and ilexible conductors of the same type y could also be formedof eight or even more conductors by varying the number and size of thegrooves in the core, and by insertin when needed several bitilar strandsin eac of these grooves or by emplo ing as a safety core a metallic wireof su cient cross section to permit of any increase in the number ofgrooves if and when required.

The alarms described above have the great advantage of being unbreakableby tension, and being incapable of division by any In addition thesecables or conductors give means without the alarm being given."

the warning signal very promptly under the action of a llame'.

. The metallic safety core, instead of being 'formed by a single groovedwire p (Fig. 2)

may be constructed, as shown in cross section in Fig. 3, of a pluralityof spaced metallic wires 9, helically wound on a central metallic wireg, and between which are interposed the biiilar conductorsa/-b and h-i,forming the various electric circuits of the alarm. The auxiliarycentral and exterior metallic wires g 1', thus employed to formthevcarrier may be bare or insulated; they may be made of steel, iron,bronze, copper or of any other metal or alloy, but it is advantageous toemploy, for this purpose, a metal or alloy of considerable hardness andtensile strength.

By simultaneousl windin around the central wire the bi lar stran s a-b,h-i, and the auxiliary exterior wires r arranged as described above, acable is obtained of which the strands comprise the auxiliary metallicwires and the bilar conductor strands interposed. For exam le in thecase of Fig. 3 which is that o an alarm cable of six conductors, therebeing three bifil'ar strands, the construction is that of a sevenelement cable composed of a central -auxiliary wire forrrling a core onwhich are helically wound three auxiliary wires and three betilarconducting strands,` the latter alternating with the former, that is tosay, each of the bilar strands is interposed between two auxiliarywires. The cable is then covered with a layer of cotton thread or othersoft material, d', and finally .with a flexible and fusible metallictube e According to the latter type, cables and flexible conductorscould be constructed with two, four, six, eight or even more conductors,the number of the auxiliary exterior wires bein varied, and ifnecessary, a plurality .of ilar strands being located in .each of thespaces formed between these wires, or an insulating central wire of adiameter greater than that of the bilar conducting strands and theauxiliary exterior wires can be emplo ed so as to admit of an increaseat need 1n the number of biflar conducting strands and auxiliary wireswithin' the periphery of the cable.

lt goes without saying that the means of insulation between the wires a,b, which arealways close together in the alarm cirl cuit can be varied,and so also can the sys- ,tem of indicators and alarm signals which areinterposed in the circuit.

I claim:

A cable of the character described comrising a carrier or supportprovided with fililicoidal grooves therein, a twisted twostrandconductor arranged in each of said grooves, each. strand of eachconductor bename to this specication the presence of ing covered with athin layer of insulating two subscribing witnesses. material and each ofsaid helicoidal grooves being of a depth at least as great as the LOUISBOBILLOT' i diameter of the twisted conductor disposed Witnesses:

therein. LUCIEN VINCENT,

In testimony whereof I have signed my E. JURAND.

